The present invention relates to a new and improved method and apparatus for securing a suture against movement relative to body tissue by using a retainer to grip the suture.
Difficulty has been encountered in securing sutures against movement relative to body tissue. A knot may be tied in a suture to prevent loosening of the suture. However, the knot weakens a portion of the suture and reduces the overall force transmitting capability of the suture. In addition, a suture which is held by a knot applies force to a relatively small area of the body tissue and tends to cut or separate the body tissue. Many operations are conducted in very restricted space where the tying of a knot is difficult.
Various methods of securing a suture against movement relative to body tissue are disclosed in U.S. Pat. Nos. 3,513,848; 4,662,068; 4,935,028; 5,306,280; and 5,593,425. Although these and other known methods of securing a suture have, to a greater or lesser extent, been successful, it is desirable to simplify the securing of a suture against movement relative to body tissue. It is also desirable to be certain that the suture applies a desired amount of force to the body tissue when the suture is secured. The overall force transmitting capability of the suture should be maximized without concentrating the force at a small area on the body tissue.
The present invention provides a new and improved method and apparatus for use in securing a suture relative to body tissue. A suture retainer may be plastically deformed to grip the suture. The plastic deformation of the suture retainer may include pressing the material of the suture retainer against the suture by cold flowing material of the suture retainer. The plastic deformation of the material of the suture retainer may be performed while transmitting a predetermined force from the suture retainer to the body tissue.
The strength of a connection between the suture retainer and the suture may be increased by forming bends in the suture before deforming the material of the suture retainer. As the suture retainer is moved along the suture toward the body tissue, the bends are moved along the suture with the suture retainer. The bends may be formed by wrapping the suture around a circular portion of the suture retainer, by moving the suture through one or more passages in the suture retainer, by bending the suture around a member, and/or by deflecting a portion of the suture retainer through which the suture extends.
The suture retainer may be gripped with a tool which is moved along the suture to move the suture retainer toward the body tissue. The tool may be used to urge the suture retainer toward the body tissue with a predetermined minimum force. In addition, the tool may be used to plastically deform the material of the suture retainer when the suture retainer has been moved to a desired position.
A suture having a known strength may be selected from a range of sizes of sutures. The selected suture. is tensioned with a force which is a function of the strength of the suture. While the suture is tensioned with the force which is a function of the strength of the suture, the suture is gripped by a retainer to maintain the tension in the suture.